The present invention relates to a pivot bearing having a radially inner bearing part and a radially outer bearing part, each of which defines a conduit for permitting a lubricant to pass through, the radially inner bearing part being supported in rotary fashion on the radially outer bearing part, and having a transmission element that communicates with the conduits to permit the lubricant to pass through.
A pivot bearing of this kind is known, for example, from DE 101 07 706 A1. The radially outer bearing part of this pivot bearing is usually attached to a larger subassembly such as a machine table. The rotatable radially inner bearing part includes the nut of a roller-type linear drive, which nut is to traverse along a stationary spindle. This arrangement permits the machine table to traverse very rapidly, even on long threaded spindles, because the speed of the radially inner bearing part is limited only by the performance data of the threaded nut and not by the critical whirling speed of the long threaded spindle.
Between the radially inner bearing part and the radially outer bearing part, a transmission element is provided, which serves to transmit lubricant from a conduit in the radially outer bearing part to a conduit in the radially inner bearing part. The latter conduit communicates with a lubrication point of the roller-type linear drive so that it can be supplied with lubricating oil via a lubricant connection on the radially outer bearing part. However, problems can arise in this connection as soon as the radially inner bearing part begins to turn very rapidly. The lubricant conduits are usually not completely filled with lubricating oil, as a result of which the centrifugal force conveys the oil into the radially outer bearing part. In particular, even lubricating oil already contained in the roller-type linear drive is conveyed back out of it, which can lead to destruction of the drive due to lack of lubrication. This problem becomes more pronounced with the embodiment according to DE 101 07 706 A1 in that the centrifugal force also conveys the lubricating oil to the lubricating point of the pivot bearing, which has a very large volume.